ES2682215T3 - Cable feed system to control the power of a welding cable - Google Patents

Abstract

Cable feed system for feeding a cable, in particular a welding cable, from a cable storage (16) to a welding or spraying torch (10) connected to and supplied by a front-wheel cable feeder (14), the cable feed system comprising the front pull cable feeder (14), a rear booster cable feeder (22) and a control unit (30) associated with the rear booster cable feeder (22), characterized because the rear booster cable feeder (22) has at least two different modes of operation between which it can be switched, under the control of the control unit (30): a prestressing mode in which a first force is applied of supply to the cable (21) that is directed towards the point where the cable (21) is deposited in the torch (10) and in which no tensile force exerted from outside the AC feeder is provided rear booster (22), and a mode of transport in which a second feed force directed towards the point where the cable (21) is deposited in the torch (10) and which is higher than the first feed force It is exerted on the cable (21).

Description

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DESCRIPTION

Cable feeding system for controlling the feeding of a welding cable Field of the invention

The invention relates to a cable feed system, in particular, for feeding a cold welding cable or metal spray cable or any other cable in applications where there is no presence of current (voltage) or any other type of signal running on the cable itself during use.

Background

Cable feeding systems are commonly used for feeding welding cables from a power source, for example, a container in which a significant amount (up to several hundred kilograms) of welding cable is stored, up to a point called welding arc where the welding cable is deposited through a welding torch, in order to join metal parts. Since the welding torch is generally connected to a welding robot and moves continuously, the welding cable must be fed through a cable guide sheathing conduit from the container to the welding torch. The passage of the welding cable through the inevitable bends and curvatures in the cable guide sheathing conduit necessarily creates a certain amount of friction and drag. More curves along the cable guide liner conduit can make the problem worse to the point that it is very difficult for the cable power system to function properly and ensure easy and necessary feeding.

In conventional welding applications, a single feeding device drags the cable from the container and feeds it to the welding torch and places it between the storage or the cable source (the container) and the welding torch (the consumer) . In some other welding applications, the power device itself contains the cable source in the form of a small reel and feeds the cable to the welding torch.

In robotic and automated applications, which are designed to maximize productivity, the trend is directed towards the use of large bulk packages containing from a few hundred kilograms to more than a ton of welding cable. These bulk containers should be placed in a safe area at a significant distance from the device that feeds the welding cable to the welding torch and preferably on the floor, in a place that can be easily accessed with a forklift. In order to comply with increasingly stringent safety standards and standards, it is highly recommended to refrain from placing containers with welding cable on top of moving robots, where the maneuver of replacing a used package with a new one It can pose a serious risk to robot operators and weight tolerances would only allow the use of containers with a limited amount of welding wire. Undoubtedly, placing the packages on the floor offers the significant advantages of allowing the use of heavier containers with more product, for maximum downtime savings and for working in a safer environment, but may result in The welding cable must be approached over considerable distances by the front feeder device from the bulk containers to the welding torch.

The transport and feeding of the welding cable over long distances, preferably through guide lining conduits placed for convenience inside the cable drag chains, is not an easy task and often the main feeder that drags the cable near the welding torch is not able to make the welding cable advance reliably. To assist the front-wheel drive feeder, systems are known that utilize the combined action of the so-called main feeder (the cable feed device near the welding torch) and the so-called slave cable feeder (a second cable feeder installed remotely from the welding torch, near the bulk cable supply vessel). Both cable feeders are controlled by a common unit or controlled using the same data source. For example, both cable feeders are equipped inside with the software and hardware necessary to synchronize their movements in such a way that the welding cable is fed to the welding torch by means of the combined drag effect of the master feeder and traction assistance of the rear slave feeder. This interaction between the two units is possible because both are normally supplied by the same manufacturer and communicate using the same protocols, but this represents, for the market, a limitation of competitiveness and an increase in costs for end users. . For example, the control data used to control the front-wheel drive feeder is also sent to the slave cable feeder so that both feeders synchronize using the same data source. WO 2005/042201, on which the preamble of claim 1 is based, shows a cable feed system comprising a front-wheel drive feeder and a slave cable feeder, in which the slave cable feeder carries the welding cable from a bulk cable supply vessel to a welding torch at a constant transport force.

In the attempt to reduce the dependence of the manufacturers of the main and slave feeders, less advanced systems are known that employ a so-called power aid booster that operates in a manner

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independent of the main cable feeder near the welding torch. The aid booster is not coupled with the front-wheel drive feeder or the torch, that is, the signals to control the front-wheel drive feeder or the torch are not used to control the rear feed aid booster, which instead detects When the cable feeder drags the welding cable, it is then automatically coupled through a mechanically controlled clutch or similar mechanical device. However, the action of the cable feeder near the welding torch assisted by the independent power booster is not as reliable and efficient as the combined synchronized cooperation of the master and slave power systems. This is due to the fact that the booster feeder always reacts with a certain delay, which increases proportionally with the length of the cable guide sheathing conduit. When the cable feeder near the welding torch starts its wire feeding action, it takes a few seconds before the rear power aid reinforcer recognizes that power is required. This is due to the inherent flexibility of the cable guide system that allows feeding a few centimeters of welding cable into the cable guide sheathing conduit (or dragging it from the cable guide sheathing conduit) at one end without the consequent immediate movement of the cable at the other end. This effect is known as slack. The same noticeable effect at the beginning of the feeding action can be noticed by stopping the feeding action. The wire feeder near the welding torch will stop without the booster feeder noticing immediately. The clearance causes the welding wire not to advance in the welding torch with the speed and speed currently requested. In other words, a non-synchronized cable traction booster that does not interact directly with the cable traction master feeder does not react promptly and accurately to the start and stop orders and the cable feed speed imposed by the Master feeder itself and this makes the entire welding process extremely unreliable. Delayed feeding assistance by the booster at the start of the feeding can cause burns on the contact tip of the welding torch and a delayed feeding interruption by the booster can cause the reinforcing rollers to scratch and deform the surface of the cable.

Since the existing power assist rear boosters are not directly activated by the front feeder and the rear booster thrust action is normally activated by a built-in magnetic clutch or an equivalent mechanical device that detects that the cable is crawling finally from the front main feeder, they often suffer from excessive overheating because the rear booster feeder motor is always in torque, also after the welding action is interrupted and the cable is not dragged by the feeder. front cable; This can contribute to considerably reduce the life of the rear booster feeder motor and can cause a fire hazard and a consequent safety problem in the welding robot cell area.

A reliable way to remotely start or stop the rear booster, and still operate independently of the main traction feeder, is represented by the prior art realization of a welding cable feed system having a motion detection device. of cable formed as a self-sufficient autonomous unit and adapted to be mounted on a cable guide, and a power assist device to assist the power welding cable based on the signals received from the cable motion detection device. This technology is based on the idea of actively controlling a feeding aid device, which acts similarly to the known slave booster feeders, using the cable motion detection device near the "main" master feeder which is usually the feeder. of cable near the welding torch. The cable motion detection device is represented by a small unit, which is physically independent of the master feeder and can be mounted in a suitable location along the cable path, preferably near the master feeder. This solution, however, has its drawbacks because in order to make the autonomous front motion detection device communicate with the rear power assist booster, it is still necessary to connect the two units through a cable that they hinder and this can represent an additional cost and complicate the configuration inside the robot cell. The inventions of the prior art also suggest a simpler way for the two units to interact through wireless communication, but this solution cannot be applied in those manufacturing facilities where Bluetooth communications can interfere with other equipment. In most, for example, automotive communications, wireless communications are often prohibited.

In an additional prior art system, a cable feed system allows reliable control of the rear booster and easy feeding of a welding cable over long distances without the involvement of a complicated or expensive system and without any need for synchronization between the master cable feeder and the aid booster feeder. This system uses the welding cable electrode itself as the means through which data and digital signals, such as voltage, are transmitted between the front feeder connection and the rear cable booster. This makes it possible to eliminate the use of clogging cables and save the cost of the motion detection device, regardless of the distance between the front-wheel drive feeder and the rear booster and the length or route of the cable guide lining conduit. With this specific system, the slave feeder, or booster, instantly detects and reacts to the presence of voltage by passing through the welding cable as soon as the welding power supply or welding machine supplies voltage and the welding arc hits at the tip of the welding torch. This

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Detection of this signal is immediate and allows to quickly start or stop the motor torque of the booster motor in connection with the actual welding action, thus avoiding unnecessary and dangerous overheating of the rear booster unit, improving the accuracy of the cable booster and increasing the life of the booster motor, with an efficiency comparable to conventional synchronization between feeder and booster. In GMAW (metal arc welding gas) and other welding processes, as soon as welding voltage and current is supplied by the welding machine and the welding arc is struck, a voltage that varies from 5 to 100 volts, It travels through the welding wire electrode. Consequently, the main cable feeder begins to drag and feed the cable from the bulk container to the welding torch, since the two actions are interconnected. This prior art system detects and exploits the presence or absence of the voltage signal in the welding cable, which is the equivalent to the start or stop of the main feeder, and moves it simultaneously, through the reinforcer components and the software gives an order to start or stop the torque of the rear booster engine. Since the rear booster and the front main feeder are not connected and the two speeds are not synchronized, the booster software can perform a variety of additional functions such as controlling the engine torque and dragging a little more than the front feeder in order to compensate for the clearance by filling with the welding cable all the free space in the curvatures of the casing, or it can stop the motor torque partially or completely after a few seconds of welding inactivity.

However, some manufacturing processes and technologies such as LASER welding, TIG welding (tungsten inert gas) or metal spray treatment of metal parts, do not imply any presence of current in the cable during feeding, and Without tension running the cable during the arc, the invention of the technique described above becomes completely useless.

It is an object of the present invention to provide a cable feed system that uses an independent rear cable booster that can operate effectively without any need for electronic synchronization with the front-wheel cable feeder.

It is a further object of the present invention to provide a cable feed system, which provides immediate support to the front tension cable feeder as soon as the front tension cable feeder begins to feed a cable through the welding torch or spray.

Summary

The cable feed system for feeding a cable according to the present invention, in particular, for transporting the welding cable from a cable storage vessel through a front-wheel cable feeder to a welding torch or a Spray torch is defined in claim 1, and further comprises a front tension cable feeder, a rear booster cable feeder and a control unit associated with the rear booster cable feeder. The rear booster cable feeder under the control of the control unit, is operated alternately in at least two different modes:

a "pretension mode" in which a first feed force is applied to the cable in order to drag it to the point where it is consumed (the torch) and where no external tensile force is detected from the rear booster feeder , Y

a "transport mode" in which a second feed force is applied to the cable by the front-wheel drive feeder in order to feed it through the welding torch with such force that it is greater than the first feed force applied to the cable In the claim mode.

The present invention is based on the idea of solving the cable feed problems caused by the slack and at the same time keeping the rear booster cable feeder in a mode of tension pretension minimally controlled so that it can react immediately to the tensile force of the front feeder as soon as a transport force is exerted by the front feeder on the cable. This prestressing mode is similar to the standby state that allows a computer to switch, after a controlled adjustment delay, to battery charge saving mode while retaining the ability to quickly resume full functions as soon as an order is detected. simple such as a mouse movement or a pressed key. In accordance with the present invention, even when the front feeder is not transporting any cables and feeding it through the torch, the rear reinforcer cable feeder continues to drag the cable towards the front cable feeder in a controlled reduced manner. This force eliminates the slack because it keeps the cable slightly dragged and easily available to feed as soon as the front feeder resumes its pulling action. As in a computer standby mode, where precise software configurations control the level of activity to allow for rapid reactivation but minimize consumption, in the present invention the rear booster claim mode can be precisely adjusted through the software. control to ensure a rapid reaction to the traction action of the front feeder and at the same time the fact that the first pretension feed force is smaller than the second transport feed force, allows the electric drive motor of the feeder to operate rear booster cable in a reduced driving impulse and in

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a significantly reduced energy consumption such that there is no risk of engine overheating even if the engine is in torque.

The state of the pretension mode can be achieved provided that no tensile force exerted from outside the rear booster cable feeder is detected within the rear booster cable feeder.

The cable booster according to the present invention can be added, retrofitted or incorporated as a stand-alone device in any existing metal welding or spraying system, without any need for synchronization with the front-wheel cable feeder.

In a preferred embodiment, the feeding system of the present invention can be combined with a sheathing conduit that extends from the cable storage to the front traction cable feeder in order to transport the cable. The cladding conduit can be equipped with or defined by numerous rollers arranged side by side and inside an outer flexible tube, in order to minimize the friction of the cable inside the cladding conduit.

The first feeding force is not enough to achieve cable transport. The first feeding force can be increased or decreased through the booster control, depending on the length or curvatures of the coating conduit: the longer the coating conduit the more the coating conduit will be curved, the greater the first Feed force will be adjusted but barely enough to neutralize the negative effects of slack and effectively prestress the cable although not strong enough to carry the cable.

The control unit switches the rear booster cable feeder between its modes of operation.

In one embodiment, the rear booster cable feeder has only two modes of operation.

The control unit switches the rear booster cable feeder from the transport mode back to the pretension mode according to an adjustable predetermined delay after detecting that the front feeder no longer drags or carries the cable. Therefore, the rear booster cable feeder does not turn off immediately after the front traction cable feeder is turned off. In most automated and robotic applications, the welding process may involve a sequence of multiple short intermittent welds, in which case delaying in a controlled manner the switching from the transport mode to the pretension mode can cause the action of the booster feeder Rear be more effective. In this case, the cable is transported for the length of a short weld, stops and is transported again in an intermittent pattern with a few seconds of pause between each weld. During the short time without welding when the front feeder stops the drag, the torque of the rear booster motor continues to operate in the transport mode and only after the inactivity of the front feeder eventually exceeds the set delay time, the control will switch the reinforcer back to claim mode. This parameter control can be specifically useful in the case of a sequence performed by many short welds followed by a short interruption of the weld: the longer the stop delay, the more the reversal will be delayed to a claim mode, guaranteeing maximum reinforcement efficiency throughout the entire sequence of short welds. When the front feeder is not dragging, it acts as a brake that holds the cable, but thanks to the prestressed mode, the rear booster feeder will not drag and scratch the surface of the cable excessively.

The control unit may have data entry options that allow a user to set or adjust the period of time to switch the booster from the transport mode to the pretension mode, then no more cable transport force is detected from the outside. of the rear booster cable feeder. Therefore, the system according to the invention can be easily adapted by the user to any type of welding sequence.

The control unit can completely control the first feed force (pretension mode) and / or the second feed force (transport mode).

The control unit monitors at least one of:

a cable movement threshold for determining the movement of cable within the rear booster cable feeder made from outside the rear booster cable feeder (i.e., by the front-wheel cable feeder), and

a cable movement stop threshold to determine the end of the cable movement within the rear booster cable feeder made from outside the rear booster cable feeder.

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The control unit may have data entry options allowing the user to set or adjust at least one of

the first feeding force (pretension mode), the second feeding force (transport mode),

a cable movement threshold for determining the movement of cable made by the front-wheel cable feeder inside the rear cable reinforcer cable feeder, and

a cable movement stop threshold to determine the end of the cable movement performed by the front-wheel cable feeder inside the rear cable reinforcer cable feeder.

The control data could be established or modified through an integrated input device (for example, a touch screen enhancer) or through an externally connected keyboard or any other electronic interface such as a computer or any other external device in order to configure, adjust and adapt the control parameters (forces, times, thresholds, etc.). The external device can be connected directly to the booster through a cable or a WLAN or wireless connection.

The first and / or second feed forces can be adjusted based on a percentage of the total driving torque potential of the electric motor, thus allowing the user to precisely control the rear booster feed action.

The first feed force (pretension mode) can vary between 1% and 50%, with a more specific preferred setting between 25% and 35% of the maximum motor torque. The adjustment of the force of the pretension mode can also be established as a percentage of the second feed force (transport mode) instead of as a full motor torque potential.

The second feeding force may vary between 50% and 100%, depending on the length and shape of the sheathing conduit used to transport the cable from the rear booster feeder to the front traction feeder.

The control unit may comprise a cable movement detection device that detects the movement of cable within the rear booster cable feeder. The cable movement detection device comprises at least one wheel (which can also be the reinforcing drive wheel) that makes contact with the cable, and in which at least one of the two parameters (cable movement stroke threshold and cable movement stop threshold) is defined by a predetermined wheel rotation speed. This cable motion detection system allows the autonomous rear booster feeder to operate independently of the front-wheel cable feeder device.

In a preferred embodiment, the rear booster cable feeder comprises at least one cable drive wheel that makes contact with the cable and a brushless electric motor to drive the at least one drive wheel. A brushless electric motor has the advantage of responding very quickly to the drive commands of the control unit and adapting itself quickly and efficiently to the requested torque settings of the two different modes of operation.

The control unit may comprise a touch control screen with memory or a PLC (programmable logic computer) or an hMi (machine man interface).

In all modes of operation of the rear booster cable feeder, a feeding force can be exerted on the cable in the direction towards the point where the cable is consumed in the torch. The control unit controls and maintains the engine at a set minimum engine torque at all times and even when running for long periods of time with a minimum engine torque, the engine (s) does not overheat easily. When the front traction cable feeder starts to drag the cable, it also causes the rear reinforcer wheel to rotate because the minimum torque established in the motor helps the tensile action, even in the presence of long lining ducts and curved

As soon as the traction action of the front traction cable feeder causes an initial movement of the traction wheel and the wheel reaches and exceeds the preset rotation speed and rotation threshold, the feeder motor of the reinforcer cable feeder Rear is activated in “transport mode” and begins to drag the cable to the preset (full) operating torque. On the contrary, when the front feeder stops dragging because it no longer needs to feed wire into the metal welding and spray gun and exceeds the preset stop wheel speed and the movement threshold, after a controlled delay time , the motor (brushless) reverts to the preset minimum waiting motor torque, thus preventing the motor and the booster from overheating and permanently damaging any electrical component of the device.

Contrary to existing prior art systems that only allow you to manually increase or decrease the cable feed speed, the present invention combines the cable pull and cable retention actions of the front feeder in the cable, with the configurations precise booster software,

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in order to order the change between two different sets of torque settings, through a dynamic interaction with traction or cable retention by the front feeder. In addition, the present invention differs from other prior art systems because the motion sensor is incorporated in the booster unit, thereby avoiding the use of clogging cables.

With all of the above embodiments, the control unit may be a self-sufficient and independent autonomous unit, that is, independent of a front traction cable feeder and the control of the front traction cable feeder and the welding control / processor. Contrary to prior art systems where the master feeder and the rear booster are directly connected and communicating through a cable, or prior art systems that employ an autonomous rear feeder / booster that drags continuously and easily overheats , or prior art systems in which current operation on the cable activates the rear booster, the present invention uses the combination of controls available through the software and the flexibility of a rear booster feeder motor for the purpose. to achieve complete independence with respect to any front-wheel drive master equipment and at the same time avoid dangerous overheating of the rear slave booster.

In applications where the welding process puts tension on the cable and the rear-tension booster is controlled by the voltage signal, and some technical problems prevent the device from functioning properly mainly due to uncontrolled voltage variations, the power system Cold cable control can conveniently become an emergency backup method to operate the rear booster without having to interrupt production.

Brief description of the drawings

In the drawings,

- Figure 1 schematically shows a welding system that includes a cable feed system according to the invention,

- Figure 2 shows the welding system according to Figure 1 in the welding process,

- Figure 3 shows a detail of a rear feeder cable feeder of the cable feed system according to Figures 1 and 2.

- Figure 4 shows the rear booster cable feeder of Figures 1 to 3,

- Figure 5 shows a touch screen with the menu configuration of the rear booster cable feeder according to Figure 4, and

- Figure 6 shows the different modes within a cable configuration.

Detailed description of the invention

In Figures 1 and 2, a welding system is shown comprising a welding or spraying torch 10 that is mounted on a welding robot 12, a front-tension cable feeder 14 for feeding a welding cable to the torch 10, and a storage or supply of welding cable 16.

In the embodiment shown, the cable supply 16 is a bulk container that can comprise a cable coil formed from several hundred kilograms of cable 21.

The cable 21 can be a cold welding cable or a metal spray cable. For both types of cable, the term "welding cable" is used throughout this specification.

The storage or supply of welding cable 16 is generally placed at a significant distance from the welding torch 10 or may even remain in a separate room or outside the welding robot cell. The welding cable 18 is guided from the supply 16 to the front traction cable feeder 14 by a sheathing conduit 20 or guide which allows the welding cable to be guided reliably to the front traction cable feeder 14 (see arrows in figure 2).

According to one option, the sheathing conduit 20 is formed from a plurality of interconnected bodies each of which rotatably supports a set of rollers in order to reduce friction between the welding cable and the conduit coating.

The front traction cable feeder 14 generally comprises at least two drive wheels between which the cable 21 is dragged. One or more of the wheels are driven by an electric motor.

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Due to the distance from the front traction cable feeder 14 to the supply 16, an auxiliary feeder called the rear booster cable feeder 22 is provided near the supply 16. The rear booster cable feeder 22 provides a drag effect in the welding cable 21 towards the front tension cable feeder 14 and the cable consumption point which is represented by the exit point of a torch 10.

Similar to the front tension cable feeder 14, the rear reinforcer cable feeder 22 comprises two wheels 26, 28 between which the cable 21 is guided and driven. The wheel 26 is driven by an electric motor, more specifically by a brushless motor from which a drive shaft 32 is shown in Figure 3.

The driving wheel 26 can be made of plastic, for example PEEK. The opposite antagonistic wheel 28 is preferably made of steel. The antagonistic wheel does not normally drag the cable, but instead holds it against the V-shaped groove of the drive wheel.

The rear booster cable feeder 22 comprises a control unit 30 that is disposed within the housing of the rear booster cable feeder.

The control unit allows data entry 32, through an integrated system, that is, a touch screen incorporated with memory. Alternatively, the control unit 30 can be connected to an external PLC device (programmable logic computer) or to an HMI device (machine man interface).

The control unit 30 is programmed to directly or remotely control the actions of the rear booster cable feeder.

The control unit 30 controls the cable feed by the rear booster cable feeder 22 based on the tensile forces exerted from outside the rear booster cable feeder 22, that is, based on the tensile force exerted on the cable. 21 by the front traction cable feeder 14. This tensile force exerted by the front traction cable feeder 14 is detected within the rear booster cable feeder 22. The feeder 22 is a self-sufficient and independent autonomous unit that does not depend No control data of the welding robot or the control unit of the front-wheel cable feeder.

The control unit 30 contains a cable motion detection device 38 comprising one of the wheels 26, 28 to which a rotation sensor 40 is coupled. Regardless of whether the wheels 26 or 28 are driven by an electric motor without brushes (symbolized by the axis 32) or by the cable 21 that is operated by the front-wheel cable feeder 14, only the movement of the cable 21 is detected and monitored. However, when the cable 21 does not move or is transported , but is kept firmly fixed by the front feeder, this is also immediately detected by a cable movement detection device. The motion detection device is always incorporated in the booster unit.

Due to the movement of the robot 12 between the welding sequences, minimal movement of the cable can occur even if no cable is effectively transported. Therefore, a certain cable movement stop threshold must be set in the control unit 30. The cable movement stop threshold determines that no more cable transport force is exerted from the rear booster cable feeder, that is, from the front-wheel drive feeder 14.

The control unit 30 also monitors a cable movement travel threshold to detect significant cable movement within the rear booster cable feeder from outside the rear booster cable feeder 22, that is, exerted by the power feeder. front pull cable 14 in order to effectively transport the cable or a slight movement of the robot 12 in a state without welding. Both the cable movement travel threshold and the cable movement stop threshold can help determine a significant movement of cable transport from a movement of untranslated cable within the rear booster cable feeder 22. Both Travel threshold and stop parameters can be set and adjusted to specific requirements by entering data through the touch screen. The control menu shown in Figure 5 offers several configuration options to adjust the thresholds. In the example shown, the threshold limit value is expressed in rPm (revolutions per minute) of the wheel that makes contact with the cable, in this case wheel 26.

In addition to allowing the user to precisely set and adjust the movement (travel) or movement thresholds (stop), the menu of the control unit and the control unit 30 also provides the ability to adjust the feeding forces exerted on the cable by the rear booster cable feeder 22. The feeding force is proportional to the motor torque of the brushless motor exerted on the wheel 26. Therefore, the adjustment of the motor torque of the brushless motor effectively controls the functions of the mode of claim and transport.

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The control unit 30 is responsible for controlling and adjusting the force exerted by the rear booster cable feeder 22 for the cable 21.

As soon as the cable feed system and the front traction cable feeder 14 and the torch 10 are turned on, the rear booster cable feeder 22 is able to operate between the two operating modes: the pretension mode and the transport mode.

In both modes, a feeding force is exerted by the rear booster cable feeder 22 for the cable 21 in the direction towards the point of consumption, that is, towards the torch 10 (consumer). Therefore, there is no way or situation in which the rear booster cable feeder 22 does not exert any feeding force on the cable 21.

In the pretension mode, a first feed force is applied to the cable 21 which is directed towards the point of consumption. However, in this mode, no tensile force exerted from outside the rear booster cable is detected, that is, from the front traction cable feeder. This is shown on the first line in Figure 6 in a first mode of operation. In this prestressing mode, the first force exerted by the rear booster cable feeder 22 is not sufficient to move the cable 21 through the front traction cable feeder 14 and outside the torch 10. However, the first force Feeding is sufficient to reduce the slack in the cable inside the sheathing conduit 20. This first feeding force is also called the "waiting force" or "waiting reinforcement" as can be seen in Figure 5.

The first feeding force can also be adjusted by the user and configured in the control unit using the menu shown in Figure 5. Since both the first and second feeding forces must necessarily be adjusted according to the length and curves of the sheathing conduit that carries the cable from the cable container 16 to the front traction cable feeder 14, it is important that the user can correctly establish and adjust both the first feed force (pretension mode) and the second feed force (transport mode). A good and reliable adjustment procedure, once the cladding conduit has been installed in the welding robot, can be to disconnect the cladding conduit from the front cable feeder and gradually increase the torque settings of the pretension motor in the control unit, until the cable can be easily dragged but cannot be fed through the single drive or the rear booster feeder.

The rear booster cable feeder 22 can be switched to a mode of transport by the control unit 30 in which a second feed force is also directed towards the point where the cable is deposited in the torch and this second feed force is significantly greater than the first feeding force exerted on the cable 21.

The mode of transport is induced as soon as a tensile force exerted by the front traction cable feeder 14 is detected inside the rear booster cable feeder 22, after the established cable movement (travel) threshold is exceeded. , as explained above. The start of the transport mode is shown in Figure 6 on the second and third lines. In this mode of transport, the rear booster cable feeder 22 significantly supports the front traction cable feeder 14 in transporting the cable 21 in the established full motor torque of the motor.

In the transport mode, a constant force and a motor torque corresponding to the cable 21 are exerted by the brushless motor.

The second feed force (also referred to as "maximum reinforcement set in%" in Figure 5) can be adjusted and configured by the user through the data entry menu (see Figure 5). Both the first and second feed forces are indicated and configured as a percentage of the maximum potential of brushless motor torque.

In the embodiment shown, the first feeding force is 25% of the total motor torque while the second force is 75% of the total motor torque that can be exerted by the brushless motor and its axis 32.

Some welding processes involve a number of short weld sequences in which the front tension cable feeder 14 stops only intermittently for a short time between welds. However, among these intermittent short welds, the rear booster cable feeder 22, instead of switching back to the first feed force (pretension mode), continues to drag the cable with the second feed force (transport mode ). Therefore, the action of the rear booster cable feeder 22 remains highly efficient and provides uninterrupted drag such that the cable 21 is transported immediately and is available for welding torch as soon as the front cable feeder resumes. the drag for a new weld.

On the contrary, in those processes that involve a long pause between welding, in order to avoid unnecessary engine operation in a complete engine torque with a risk of overheating the device

and the scratching of the cable surface, excluding those situations in which the rear booster cable feeder 22 operates in accordance with a precise programmed feeding sequence, after a preset and controlled delay, the motion sensor of rear booster detects that a force is not exerted to the cable by the front pull-wire cable feeder 14, and the control unit 30 5 switches the rear booster cable feeder 22 back to the prestressing mode. This established time delay, also called "stop delay" in Figure 5, can be adjusted by the user through the control unit configuration menu.

The aforementioned function of the rear booster cable feeder 22 is independent of any sensor external to the rear booster cable feeder 22.

An optical sensor 40 can be connected to the control unit 30 with such an optical sensor 40 positioned close enough to the torch 10 to be able to detect the light generated by the arc in the torch 10.

15 However, in all embodiments, the control unit may be a self-sufficient and independent autonomous unit.

Claims (11)

5 10 fifteen twenty 25 30 35 40 Four. Five fifty 55 60 65 1. Cable feed system for feeding a cable, in particular a welding cable, from a cable storage (16) to a welding or spraying torch (10) connected to and supplied by a front-wheel cable feeder (14 ), the cable feed system comprising the front traction cable feeder (14), a rear booster cable feeder (22) and a control unit (30) associated with the rear booster cable feeder (22) , characterized in that the rear booster cable feeder (22) has at least two different modes of operation between which it can be switched, under the control of the control unit (30): a prestressing mode in which a first feed force is applied to the cable (21) that is directed towards the point where the cable (21) is deposited in the torch (10) and in which no tensile force is provided exerted from outside the rear booster cable feeder (22), and a mode of transport in which a second feeding force directed towards the point where the cable (21) is deposited in the torch (10) and which is higher than the first feeding force is exerted on the cable (21). 2. Cable feed system as in claim 1, further comprising a sheathing conduit (20) extending from the cable storage (16) to the front traction cable feeder (14), defining the sheathing conduit (20) a means of transport for the cable (21). 3. Cable feed system according to claim 2, wherein the first feed force is adapted to the length of the welding cable (21) from the cable storage (16) to a consumer and to the cable friction welding (21) inside the cladding conduit (20) in order to move the welding cable (21) into the cladding conduit (20) and reduce the cable clearance, without moving the cable (21) out of the feeder of front-wheel drive cable (14). 4. Cable feed system according to any of the preceding claims, wherein the control unit (30) switches the rear booster cable feeder (22) between its modes of operation. 5. Cable feed system according to any of the preceding claims, wherein the control unit (30) switches the rear booster cable feeder (22) from the transport mode to the pretension mode from a predetermined period of time after detecting that no more cable transport has been generated from outside the rear booster cable feeder (22), more particularly in which the control unit (30) is configured to control and modify the force exerted by the rear booster cable feeder (22), the control unit (30) having a data entry (34) for a user that allows the user to modify the predetermined period of time after detecting that it has not been generated plus cable transport from the outside of the rear booster cable feeder (22). 6. Cable feed system according to any of the preceding claims, wherein the control unit (30) is configured to control and modify the force exerted by the rear booster cable feeder (22), in particular, wherein the control unit (30) controls at least one of the following parameters: - the first feeding force, and - the second feeding force. 7. Cable feed system according to any of the preceding claims, wherein the control unit (30) monitors at least one of - a cable movement threshold for determining the movement of cable within the rear booster cable feeder (22) made from outside the rear booster cable feeder (22), and - a cable movement stop threshold to determine the end of the cable movement inside the rear booster cable feeder (22) made from outside the rear booster cable feeder (22). 8. Cable feed system according to any of the preceding claims, wherein the control unit (30) has a data input (34) for a user that allows the user to modify at least one of - the first feeding force, - the second feeding force, - a cable movement threshold for determining the movement of cable generated by the front-wheel cable feeder (14) inside the rear booster cable feeder (22), and - a cable movement stop threshold to determine the end of the cable movement generated by the front-wheel cable feeder (14) inside the rear cable reinforcer cable feeder (22). 9. Cable feed system according to claim 8, wherein the control unit (30) comprises a cable motion detection device (38) that detects the movement of cable within the rear booster cable feeder (22), the cable motion detection device (38) comprising at least one wheel (26, 28) that makes contact with the cable (21), and in which at least one of the threshold 5 of cable movement and the cable movement stop threshold is defined by a predetermined wheel rotation speed. 10. Cable feed system according to any of the preceding claims, wherein all modes of operation of the rear booster cable feeder (22) are designed in order to exercise 10 a feeding force on the cable (21) in the direction towards the point of consumption, that is, the welding or spraying torch (10). 11. Cable feed system according to any of the preceding claims, wherein the control unit (30) is a self-sufficient and independent autonomous unit. fifteen